The present invention relates to a device for feeding vapors present in the free space of a fuel tank into the intake manifold of an internal combustion engine. The free space and the intake manifold are connected by a line in which an activated carbon container and a stop valve are arranged in series. The activated carbon container is connected to the atmosphere by a vent line which can be closed off by a valve.
Such a device is known from DE-PS 40 12 111. Proceeding from a device according to DE-PS 38 02 664, corresponding to U.S. Pat. No. 4,901,702, the specification of which is incorporated herein by reference, there is arranged in addition, between the electromagnetically actuatable valve and the intake manifold, an auxiliary valve which can be sealed by a vacuum controller and which has a control chamber. In order to prevent the fuel-air mixture drawn in by the internal combustion engine from becoming excessively rich at low operating speeds of rotation of the internal combustion engine and/or upon a particularly high degree of saturation of the absorption element, the stop valve has the auxiliary valve connected in series directly in front of it. The auxiliary valve comprises a vacuum controller which consists of a rubber-elastic adjusting diaphragm and a compression spring, the auxiliary valve having a separate closure element which rests on one side against the adjusting diaphragm by means of a support collar and on the other side against the compression spring.
A leakage testing of the system shown in DE-PS 40 12 111 is effected by a valve which, during the testing, closes off the vent line which is open towards the atmosphere, the testing region being located during the test cycle between the stop valve which is also in a closed position and the tank installation of the internal combustion engine. The development of the valve, however, is not described.
The device shown in DE-PS 41 00 659, corresponding to U.S. Pat. No. 5,220,897, the specification of which is incorporated herein by reference, is provided with sensors in order to monitor its operability. The sensors transmit the actual measured values to a diagnostic unit, which compares the actual values with predetermined desired values. A testing of the device for leakages during operation is not incorporated in that system.